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AMPREDICT Decision Support Tool for Veterans with limb loss

January 27, 2022

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Photo: ©Getty Images/FatCamera

Choosing the optimum amputation level for people who need a limb removed is a challenge for both physicians and patients. In 2021, VA researchers and researchers with the University of Washington unveiled a decision support tool, called AMPREDICT, that allows doctors and patients throughout the world to work together to determine the best level of amputation for those with chronic limb threatening ischemia (CLTI). The tool, it is hoped, will also reduce variability among providers. It is now available online for clinicians and patients throughout the world to use.

Ischemia is a serious condition in which there is inadequate blood flow and oxygen to various parts of the body. In the limbs, the disease can cause severe tissue damage, including skin ulcers and gangrene. CLTI is an advanced form of peripheral artery disease (PAD), and is considered a medical emergency that brings significant risk of complications and death. If there is insufficient blood flow to an extremity, doctors may have to amputate the limb or limbs. Many patients with CLTI also have either diabetes or atherosclerosis (hardening of the arteries). PAD progresses more rapidly in patients with diabetes, and the risk of developing CLTI is four times higher for diabetic patients than for those with atherosclerosis.

The decision on how much of a leg or arm should be removed must integrate the combined risks of the remaining part of the limb failing to heal, the mobility of the patient after the amputation, and the possibility of death after the amputation is completed.

The AMPREDICT decision support tool is a patient-specific predictive model of mobility (the ability to move freely and easily) in people undergoing their first major lower extremity (leg) amputation because of complications of diabetes or PAD. It predicts the probability that a patient will achieve independence in basic or advanced mobility 12 months after amputation at each level of limb removal. Such levels include amputations of the foot, at the ankle, below the knee, at the knee, above the knee, and at the hip.

The model considers a spectrum of demographic, comorbidity (other diseases the patient may have), psychological, and social predictors collected during the period before surgery takes place. It allows surgeons to predict how much mobility patients will have at each amputation level so they and their patients can decide together on how much the limb should be reduced. It also aims to reduce variability among surgeons on how much limb is reduced on patients with similar characteristics and disease levels.

Studies were conducted among Veterans between 2005 and 2014. These studies determined the decision support tool could, in fact, predict mobility levels a year after surgery. Following those tests, an online version of the tool was developed and tested by 10 VA clinicians from around the nation. The 10 clinicians provided their thoughts on the model, and, in 2021, a web-based user friendly portal was launched for clinicians throughout the world to use. It provides immediate calculations that estimate whether re-amputation might be needed, the amount of mobility a patient might expect a year after surgery at various levels of amputation, and the risk of death following different amputation levels.

VA is now integrating the tool into its electronic health records system for use throughout the nation, and is doing testing to determine how well the tool assists with shared decision making between Veterans and their clinicians.

Principal investigator: Dr. Daniel C. Norvell, VA Puget Sound Health Care System

Selected publications:

The development and usability of the AMPREDICT decision support tool: a mixed methods study. Norvell DC, Suckow BD, Webster JB, Landry G, Henderson AW, Twine CP, Robbins JM, Czerniecki JM. Eur J Vasc Endovasc Surg. 2021 Aug;62(2):304-311.

The development and validation of the AMPREDICT model for predicting mobility outcome after dysvascular lower extremity amputation. Czerniecki JM, Turner AP, Williams RM, Thompson ML, Landry G, Hakimi K, Speckman R, Norvell DC. J Vasc Surg. 2017 Jan;65(1):162-171.e3.

Physicians call for clinical application of “helpful, meaningful” AMPREDICT decision support tool, vascularnews, June 10, 2021

www.ampredict.org



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